This invention relates generally to multi-section, high speed, motor driven, impact-resistant folding doors and is particularly directed to an improved seal for the lead, or center, panels of a multi-section folding door.
Electrically operated folding partitions, or doors, having a plurality of vertically oriented panels are commonly used in doorways to provide isolation between two rooms or between the outside and inside of a building. Such folding partitions are also frequently used to divide off two or more areas of a given room. The vertically oriented panels are typically suspended from a longitudinal, horizontal track along which the panels are movable. The panels may be coupled together in an accordian-like manner or they may be detached from one another such as in a strip door. Where the panels are coupled together, they are automatically positioned in a straight line, flat arrangement when in the fully closed position and are automatically moved to a folded, stacked configuration when in the fully open position. Such structures are often referred to as operable walls in that they provide a movable wall section for space isolation purposes.
These types of multi-panel folding doors are frequently sometimes used in low temperature environments to isolate those areas on opposing sides of the door. Perhaps the most common low temperature application of these doors is in freezers. In this environment, the individual panels are preferably comprised of materials capable of withstanding low temperatures without deforming or cracking particularly upon impact by a moving object such as a vehicle. When the door is open, there is inevitably a reduction in the temperature differential across the doorway. Present multi-panel folding doors offer only a limited insulating and sealing capability when closed for isolating adjacent spaces separated by the door. Available folding doors are subject to heat leakage particularly in the area of the overlapping lead, or center, panels and thermal transmission through the individual panels which are thin and lightweight because of the high speeds at which those doors are required to operate.
The present invention is intended to overcome the aforementioned limitations of the prior art by providing a multi-panel, high speed folding door having insulated panels which are particularly adapted for use in low temperature environments such as in freezers. The two lead, or inner, panels are provided with respective overlapping collapsible nose seals which incorporate a magnetic coupler for an improved seal in the center portion of the door. Each panel includes a center transparent, sheet-like partition and an insulating sheet on each side of the transparent partition with aligned apertures for more easily and inexpensively providing the panel with a window.